1. Field of the Invention
The invention relates to a film for construction, especially a vapor control layer, a counter ceiling web and an underform web, with at least one functional layer, and optionally, at least one other layer, especially a carrier layer and/or reinforcing layer, the functional layer having a water vapor diffusion resistance (sd value) that is dependent on the ambient humidity. Moreover, this invention relates to a film combination with at least one film of the aforementioned type, and optionally, with at least one other film connected to the film and/or with at least one carrier connected to the film.
2. Description of Related Art
Heat insulation measures are known on buildings, parts and equipment in order to save energy, on the one hand, and on the other hand, to protect components against damage, for example, by condensate formation when moisture penetrates by convection or by diffusion. Therefore, control of convection and diffusion processes plays a decisive role in the construction field. In particular, insulation can thus be improved and its function can be permanently maintained.
In particular, controlling water vapor diffusion can prevent moisture damage. For this purpose, if vapor barriers with high diffusion resistance are used, the construction is indeed protected against penetrating moisture due to diffusion processes; but, vapor barriers have the disadvantage that drying of the inside is prevented or hindered. If vapor control layers with low diffusion resistance are used, redrying is possible, but there is the danger of overly great wetting as a result of diffusion processes.
In this connection, the prior art discloses films with variable water vapor permeability. Vapor control layers are preferably used here with a water vapor diffusion resistance or variable sd values that are dependent on the ambient humidity and they can also be located around the rafters in an undulating manner, for example, in the roof area in addition to installation over or under the rafters.
German Utility Model DE 296 11 626 U discloses a barrier for prevention of air convection and emission of pollutants from components in the rooms of buildings, on the room side there being a polyamide film. The film can consist of polyamide 3, 4, 6, or 12 or of a mixed polyamide. At a film thickness of 50 microns the film under measurement conditions according to DIN 52650 in a dry region at an average relative humidity of roughly 30% has a water vapor diffusion resistance (sd value) of 4.5 m and in a humid region at an average relative humidity of roughly 70% has a water vapor diffusion resistance (sd) of 0.5 m of a diffusion-equivalent air layer thickness.
German Patent DE 102 39 985 B4 discloses suitable sealing strips 5 to 20 cm wide for construction engineering that are formed of at least three flat layers, the middle layer consisting of a film of an ionomer that has a lower water vapor diffusion resistance at higher relative atmospheric humidity than at a lower relative atmospheric humidity, the film at 72.5% relative atmospheric humidity having a sd value from 0.1 to 5 m and at 25% relative atmospheric humidity having a sd value from 1 to 10 m and the difference of the two values being 0.5 m or greater. The two outer layers that protect and carry the middle layer consist of the same or different material and have a sd value that is below the lowest sd value of the film. Moreover there can optionally be other layers of water vapor-permeable framing materials and/or process engineering auxiliary materials. Comonomers can be different synthetically based monomers.
German Patent Application DE 101 11 319 A1 discloses a material for a film for lining buildings or for covering components, such as walls, floors, rooves and ceilings in buildings or for a vapor control layer for heat insulation in buildings, at least some of the material consisting of polar materials and having a water vapor diffusion resistance (sd value) that is dependent on the ambient humidity. At a relative humidity in the range from 20% to 60% or 30% to 50% the sd value is 5 to 10 m diffusion-equivalent air layer thickness and at a relative humidity in the range from 50% to 95% the sd value is less than 2 m or less than 1 m diffusion equivalent air layer thickness. Some of the material can consist of a polymer in which polar ingredients such as an ionomer resin with ethylene and methacrylic acid are contained. Moreover, some of the material can consist of an ethylene-based polymer or copolymer material, such as polyethylene or polypropylene to which acrylic acid is added.
German Patent Application DE 102 31 769 A1 describes a vapor control layer film with increased breaking elongation in the lengthwise and transverse directions and with variable water vapor permeability. The vapor control layer film consists of a copolyamide, by which increased breaking elongation in the lengthwise and transverse direction of the vapor control layer film will be achieved. The vapor control layer film at an ambient atmosphere pressure of 100% and an ambient temperature of 0° C. should have a water vapor diffusion resistance in the range from 4.5 to 8 g/(m2d) and at a relative humidity of the atmosphere surrounding the vapor control layer film of 85% and an ambient temperature of 23° C. should have a water vapor diffusion resistance in the range from 11 to 23 g/(m2d).
The vapor control layers and films known from the prior art generally contain petrochemical-based polymers that must be disposed of after their use with high energy expenditure and with great complexity. This is associated with high costs. With petrochemical-based polymers, only amide or ionic functionalities are used.